This is how I make fuel lines...
The lines are interchangeable among my Cubs because I'm careful to have all the sediment bowls tightened so the outlets are all pointing the same way -- at right angles to the center line of the tractor (THIS IS IMPORTANT FOR THIS SYSTEM TO WORK). If you do the same you should be able to make a new line that fits the same way. This also assumes the sediment bowl and IH carburetor have the original threads.
This won't work for tractors with underslung exhaust without some modification.
The line is made from a 20" length of 5/16" brake line available from NAPA with the right fittings already on it. The fittings are the correct 1/2" x 20 thread. The flared ends are cut off and ferrules are used instead. The ferrules will have to be bought separately.
Here's one of my lines with the measurements that work for me:
I recommend making the first bend just a little long and trimming it to the final length. Note the measurement is from the center line of the vertical run to the end. The vertical run is measured between the center lines of the two horizontal runs. The final horizontal run is simply measured from the center line of the vertical to the final end cut.
It may be helpful to note any difference between expected length of the first run and the final result -- so the layout of the second bend can be adjusted accordingly, if necessary.
There are several ways to make the bends. I'll only explain the one I use. Since I don't have a proper bender of the right size I use an old pulley made for round leather belts that makes a 2" radius bend.
I clamp the pulley in the bench vise so I have both hands free. The desired length is measured on the line and the radius is deducted and the spot marked. By placing the mark on the pulley at the point of tangency, the right length will result when the pipe is bent 90 degrees.
Here's where you have to be really careful ... make the second bend in the right direction!